The biggest concern is the runout of the carrier(and the ring gear).Once you get runout OK,backlash variances should go away.
I prep the carrier ring gear mounting surface with a fine flat file,don't remove any material from the surface just get rid of burrs and dings. I prep the ring gear mounting surface with a 'stone flat'.
When I still get runout after that,I pull the ring gear and measure the runout(with the shims in and caps torqued) of the carrier's ring gear mounting surface. If the carrier isn't running true(I consider .001" acceptable),the carrier could have been thru a catastrophic event and caused the ends of the carrier(where the bearings are pressed onto) to no longer run true. This is a 'wooble' of the carrier as you're rotating it in the housing. I had a carrier once that had a 1/8" wobble that resulted from a ring gear bolt coming loose and hit in the mesh of the ring/pinion gears. That was the worst I've ever seen.

 

Thanks for the advice first year. I guess my next step is to remove the ring gear and measure run out on the carrier to see if I'm ,001 or less. Then go from there.

 

I took off the ring gear and I'm getting .004 runout measuring from the side of the carrier's ring gear mounting area. I'm getting .002 verticle runout when measuring from the machined ring gear hub area.

I noticed this today. The left side carrier bearing looks out of round. The top of the bearing cage looks tighter than the bottom. Can changing the bearing be the answer to my problem?

 

An important rebuilding tip I found out the hard way.

Measure run out before installing the new ring gear.

 

This is where I'm at right now. I'm going to change my one suspect carrier bearing and put it all back together whether I have run out still or not.

I can use some advice on the patterns I already had done this far.

The first two pics show a .034 factory pinion shim which seems too shallow.

The next 2 pics, to me show a good pattern, accept for the fact the coast is closer to the heel and the drive is closer to the toe. Would that indicate I'm too deep? I can't seem to find my notes right now but I believe I had a .040 pinion shim here.

And last picture shows a .038 shim.

I went thicker with the pinion shim but it showed too deep, the pattern was cut off near the flank. All patterns were between .007-.011 backlash.

What are your guys opinions?

 

Second pattern looks best to me, but they all look do able. Bearing may or may not be bad, the cage really just keeps the rollers in place. It can be out of round without the bearing being bad or might just be shaking back and forth a little bit. Could have been bent from getting smacked on an install etc as well..

 

I got the new carrier bearing on there, now it's just finding the time to get this thing altogether again.

Thanks for feedback grngry. Any other opinions on the 2nd pattern. Would you try and tweak it? Or would that be a quiet pattern based on builds you guys have done in the past?

 

I figured out what caused my .004 backlash variation. It was my 3 channel abs tone ring not being flush with the carrier flange. I put my flat stone across the ring gear mounting area and tone ring and the tone ring was sticking up a little less than an 1/8 inch. Hammered it down flush with my punch.

I added .002 thousand pinion shim and loosened up my backlash .001. I'm happy with my pattern and I'm getting .006-.007 backlash.






I made a mistake with my ratech solid spacer. On my first attempt, I installed its shims first and then the spacer not noticing the shoulder where the solid shims sit on the pinion was thinner than the shims. So the shims got bent inwards and I didn't trust them anymore. So I picked up another 4111 kit from ratech.

Tomorrow, I'm getting a shop to press on my pinion bearing.

I'm thinking I may through the smaller pinion bearing in tin foil on the bbq for a bit to help it fit onto the pinion better. Seemed I had to take off almost as much material for set up on the small bearing compared to the big one. I feel I would **** something up if I just screwed it on with the old pinion nut. Anyone have issues seating the smaller bearing?

 

I finally got my baby back together and on the road. Definitely my most stressful install compared to poly mm and fishing a broken dipstick in my oil pan with a magnet, lol. Always an adventure with this beast.

Final preloads

Pinion 22in lbs
Carrier + pinion 28 in lbs
Carrier preload (28-22) x 3.73gears=22.38
22+22=44 total preload
Backlash 6-8 thou





Coast



Drive






My case spreader. I copied Firstyr's template but added 5/8 bolts I already had that dropped into the spreader holes perfectly. It spread the case about .004 and then I beat the carrier in as well for my final preload.

My motive rebuild kit really sucked in my opinion. Pinion seal was too big and they were cheap on the pinion and carrier shims. I would not have been able to adjust the carrier where it should be if I used their shims. Instead I picked up a yukon Super shim kit and it came with every shim imaginable and you can adjust whatever you need to with ease. Plus there is a groove in the 2 larger shims that hold the little shims so it is impossible to damage any shims.

I drove the car for 2 heat cycles and so far, no abnormal noise. Drove in the city, hit about 50mph max. If you listen carefully you can hear a little howl but its very very faint and is there on both drive and coast so I would says its just the 3.73s.
Im dying to punch it on every turn I make and fish the rear end haha, Im soo glad to have my car back on the road.

Thank you ls1tech peeps for the help with the rebuild. I learned a lot from 01ss and Firstyr's posts plus many other members past posts as well. I will update the thread with after break in pattern, 1/4 mile and SITP inprovements as they come.

Last question, I bought Blue box motive 3.73s but the actual stamped part number on the gears was G8xxx373. I though G8s were the orange box part numbers. I dont care either way, just curious which motives I was shipped.




My T/A

 

Congratulations on getting it done. I remember that break in period when we rebuilt mine and put the Motive 3.90s in. So tempting not to punch it! Mine has a slight whine only when decelerating but like yours, it could be just the gears. Did you go with a girdle cover? I did in mine and it makes draining and filling the rear differential fluid a breeze.

 

Thanks Jad! Yes my car already had a mac girdle. With the girdle, solid spacer and full rebuild, I should be good for a while.

 

I finished my break in this week and changed the fluid. Everything looked good, nothing abnormal. Summit sent me Orange box motives in Blue box packaging which I'm fine with. The gears do whine a little on accel (50-65) if you listen for it. I'm not worried about it at all, especially since I found out I was sent Orange box motives.





Painted a few spots on drive and coast, all looked the same

One of my favourite mods I have done to my car. The car is ready to take off in any gear at any time now. My street tires have their hands full with these 3.73s. Car kicked out completely sideways banging 2nd gear, car feels like I added a third ******** or some ****. Im surprised I felt this much improvement going from 3.42-3.73s. Crusing around town in 5th or 6th is effortless compared to the 3.42s. 4.10s and a set of drag radials would be interesting to feel. All in all, this task took me wayyyyyyy too long but it was definitely still worth it.

 

What width tires are you running? I had to switch to a 285/35-18 cause the 275s were too sketchy. The 285s still working pretty hard to keep it straight. Don't be like them Mustangs and find a crowd! Lol

 

Lol, you don't know the other half of the story. Funny thing was, that happened leaving a car show, lol. Unlike a mustang coffee and cars clip, I got off the gas instead of staying in it and crashing. I am running a 275-40-17. When they are warmed up, that aren't AS sketchy

 

Your language skills are amazing, you must be a highly educated person, with a superior command of the English language.

JMHO